Quadruped Hind Leg Anatomy

The below series of photographs use McGregor Museum specimens to illustrate the ancestral similarities (synapomorphies) and derived differences (apomorphies) between the hind leg of different quadrupedal mammals.  Keep in mind the habit and locomotory behaviour of these animals as you compare their limb structure.

Here the leg of a goat (Capra aegagrus) represents the unguligrade anatomy of locomotion.

Likewise, the hind leg of the leopard (Panthera pardus; left) and european hare (Lepus europaeus; right) illustrate the digitigrade’s anatomy.

The above black bear (Ursus americanus) hind limb is representative of plantigrades anatomy.

Columba livia (rock pigeon brain)

The brain of a rock pigeon entire from above (top left), entire from below (top right), entire from the lateral left (middle left), vertical-longitunal section (middle right) and horizontal longitudinal sections with increasing depth on each side left to right (bottom two diagrams).  Major regions of the brain shown are the cerebral hemispheres (large, paired, round, grey structures), pineal body (red structure between cerebral hemispheres from above), optic lobes (yellow and round, beneath and posterior to cerebral hemispheres), cerebellum (folded structure, central and posterior), and medulla oblongata (gold, paired central structures at very posterior).

Gadus morhua (Atlantic Cod)

Sketches showing the anterior internal anatomy of an atlantic cod.  The left image highlights the vasculature of the blood circulatory system (oxygenated in red, de-oxygenated in blue).  Note the high levels of vasculature surrounding the gut (transportation of absorbed nutrients) and rete mirabile of the swim bladder (control volume of oxygen in swim bladder via root effect).  The capillaries of the gills have been omitted in the left image but are present in the one on the right.  The right hand image also illustrates well the alimentary canal complete with a blind ended pouch in the stomach, the mid-gut caece for enzyme production and absorptive intenstines.  The latter image also shows the skeletal framework, kidneys (red below spine), gall bladder (green), swim bladder (white and frilly, below kidney), and the gonad (red, connected to vent).

Canis lupus

Canis lupus is most commonly referred to as the wolf.  With 39 subspecies the morphological variation amongst members of this species is in some ways subtle, asthetically it is diverse.  The sub-species commonly referred to as the domesticated dog (Canis lupus familiaris) is most probably derived from the more ancient lineage of asiatic/arab wolf (Canis lupus arabs).